This photo is the oldest Taegeukgi(Flag of South Korea) in the world that Bureau of Navigation in US Navy Department published “Flags of Maritime Nations” in July 1882 on.
It is written “大清国属高麗国旗” in the photo in Han Language.
“大清国属高麗国旗” means “The Great Qing Dynasty’s subject Goryeo Flag”…
South Korea was a subject state of China on the real history.